To bring about homogenization and temperature equalization in a melt and to improve reaction conditions in connection with refining, degassing and alloying of the melt, the melt is stirred. By allowing a low-frequency magnetic travelling alternating field to act on the molten metal, sufficient electromagnetic forces are generated in the melt to achieve a good and controllable circulation in the melt. This circulation stirs the melt such that the desired improvements regarding homogenization and reaction conditions are achieved.
During the treatment, the melt is contained in a container, preferably an essentially cylindrical ladle or crucible, and a low-frequency magnetic travelling alternating field, which is generated in a coil arranged outside the container, is applied to the melt.
A problem which arises when a magnetic alternating wall is applied to act through a container wall are the losses which occur in the wall, especially when the wall comprises a magnetic material.
Usually, this problem is solved by designing at least that part of the container wall, through which the low-frequency magnetic alternating field has to pass to act on the melt, of a non-magnetic material. Especially in connection with ladles in which a molten metal is contained during transport, refining, degassing, alloying, holding and/or casting, this leads to increased costs because conventional steels cannot be used for that part of the shell of the ladle through which the magnetic alternating field is applied.
One object of the invention is to suggest a method, in inductive stirring of a melt, of applying a low-frequency magnetic travelling alternating field to act through a wall, which comprises at least one layer of a magnetic material.
Another object of the invention is to suggest a device suitable for inductively stirring a melt contained in a container whose walls comprise at least one layer of a magnetic material.